APNEIC: an easy-to-use screening tool for obstructive sleep apnea

Taking the measurements

The Mallampati pharynx grade is obtained by asking patients to open their mouths and stick out their tongues as much as possible. If the pillars of the tonsils are visible then the pharyngeal grade is less than III (Figure 1). Avoid asking patients to say “ah” and do not use tongue depressors, as these maneuvers will cause an underestimation of the pharyngeal grade. Neck circumference is measured at the level of the cricothyroid membrane.

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Figure 1

Grades II and III of the Mallampati pharyngeal grading system. A grade of III or IV applies if the pillars of the tonsils are not seen.

The presence of an overbite is determined by asking patients to close their mouths normally then retract the lips (ie, “Show me your teeth while keeping them clenched”). If the upper teeth are in front of the lower teeth, an overbite is present. The cricomental space is measured by putting a straight edge (eg, a ruler) between the cricoid cartilage and the inner chin, while the patient holds his or her head in the neutral position. This cricomental distance is then bisected and the perpendicular distance to the skin of the neck is measured (Figure 2).3 Using a thick instrument such as a tongue depressor should be avoided, as it might cause a slight underestimation of the cricomental distance.

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Figure 2

The cricomental space is the distance between the neck and the bisection of a line from the chin to the cricoid membrane when the head is in a neutral position

Adapted from Tsai et al.3

If the cricomental distance is greater than 1.5 cm, OSA is very unlikely; in one study, the negative predictive value was 100%.3 If the cricomental distance is less than 1.5 cm, then the other 5 factors should be considered—the more of them that are positive, the more likely a diagnosis of OSA. Tsai et al demonstrated that having a cricomental distance of less than 1.5 cm, a pharyngeal grade of III or IV, and an overbite prompted a positive predictive value of 95% for OSA.3

Alternative screening tools

The Berlin questionnaire4 and the STOP questionnaire5 are other screening tools for OSA, which are based on historical attributes (history of loud snoring, history of daytime somnolence, etc); both questionnaires have positive predictive values of approximately 50% and negative predictive values of approximately 70%. The STOP questionnaire, which involves questions about snoring, daytime tiredness, observed apnea, and high blood pressure, is a sensitive screening tool.5 It can therefore be combined with the clinical attributes described above and can be remembered using the mnemonic STOP APNEIC.